Discard any shellfish with broken shells or that do not shut immediately when sharply tapped.

Cut the fish into chunks.

Heat 4 tablespoons of the oil in a flameproof casserole, add the fish and cook over medium heat, stirring occasionally, for 5 minutes, then add the bell peppers and shellfish, lower the heat, cover and cook until the shells open.

Discard any shellfish that remain closed.

Meanwhile, heat the remaining oil in a pan, add the onion and cook over low heat, stirring occasionally, for 5 minutes until softened, then stir in the rice.

When the rice has changed color, pour in the stock, stir in the garlic and cook for 12 minutes.

Pour the rice into the casserole, mix well, increase the heat and cook for a few minutes more.

Drizzle with oil and season with salt and pepper.

Transfer the casserole to the oven and bake for 5 minutes.

Serve straight from the casserole.

There are numerous versions of this classic Spanish dish. Some recipes include artichoke wedges, chicken, pork, turkey, smoked bacon or saffron, depending on the region.